Ketosis, a mystery word bandied about by those who have delved so deeply into the mysteries of dieting and human physiology that everybody else, the normal folks who still talk wonderingly about the benefits of cutting refined carbs, are left gaping and wondering what on earth they're going on about. What is Ketosis? How do you induce it in your body? What are its benefits, and is it really the ultimate way to burn fat for those with the will power to adhere to its brutal requirements?
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Ketosis is basically a metabolic state that occurs when fatty acid oxidation is raised to such high levels that your liver can't process them all, and they are instead shunted into your blood stream. This occurs when you are literally starving, with super low carb diets, and extreme endurance sports. Basically it's what happens when you're getting no carbs, resulting in a massive drop of available glucose levels, so that your body is unable to burn its preferred energy source and must instead turn to fatty acids.
When this happens, fatty acids are only partially oxidized. This causes an excess amount of acetyl-CoA to be produced, which is converted into ketones. When you get enough ketones in your body, you are in the state of ketosis. Simple, right? The whole point is that ketones are derived from fat, and causes your body to use them as a source of energy instead of glucose.
The reason people get excited is because ketones are an inefficient way of burning fat. By forcing fatty acids to be turned into ketones first before being used as a source of energy, you are burning more fat for the same output. Second, ketosis is protein sparing. When in ketosis, your body is relying less on protein synthesis and this means less body protein needs to be broken down to make glucose. So everybody thinks: bette fat burning, less muscle break down - great!
But the reality isn't so amazing. People who are lean (15% body fat or less) don't really get the protein sparing effect, due to their inability to mobilize enough fat into ketones due to being too skinny to begin with. The second argument that mobilizing fat into ketones is an inefficient way to do so is true but to such a small degree that it doesn't really make much of a difference. Further, the state of ketosis is awful; you feel light headed, fuzzy brained, drained and exhausted the whole time. So is ketosis the ultimate way to burn fat? Sorry folks. Not really.
Ketosis is a state in metabolism when the liver converts fat into fatty acides and ketone bodies which can then be used by the body for entergy. This is not to be confused with "ketoacidosis" which is a dangerous condition that is it good for your body to be in ketosis can occur with diabetes. Ketosis is the state that we all want to reach to lose weight. Ketones are molecules generated by the liver during fat metabolism and are a normal source of fuel and energy for the body. Diets that restrict calorie intake cause weight loss, however, some of the weight loss is from fat and some of it is from lean muscle tissue. The loss of lean muscle tissue slows the metabolism making weight loss more difficult and also makes regaining weight easier.
When your body is in ketosis, it is using fat as its' primary source of energy. If you are consuming adequate protein, your body will not break down muscle tissue. One your liver has converted fat into ketones, they cannot be converted back to fat and stored, so the body must excrete the molecules in your sweat and urine.
Many people falsely believe they cannot or are not losing weight because the ketones drop to a lower level. This means that Ketostiks which are used to measure the ketones in the urine, are no longer showing the purple color on the test strip, but weight loss continues with or without the ketones being present. The excess ketones excreted in the urine disappear on a low-carbohydrate diet after the body becomes accustomed to using dietary fats for energy instead of glucose. This usually occurs within a few weeks on the diet. People who normally eat high-carbohydrate meals have been fueling their bodies from the glucose and fructose obtained from the carbohydrates. Their cells have had very little experience burning fatty acids for energy. The body uses the glucose first to prevent high levels of glucose in the blood.
The body experiences a new condition when a person goes on the low-carbohydrate diet. The more commonly used glucose fuel is no longer available. The body reacts by dropping the pancreas' production of insulin and increasing the hormone glucagon. The glucagon draws stored fat reserves in the form of triglycerides for use by the cells as the new energy source. However, the cells are slow to react to this new fuel source, and the individual feels weakness or a lack of energy. The resistance to burn fatty acids for energy can vary greatly between individuals. Some people feel weak while others have a feeling of greater energy than before.
The liver begins to catabolize (break down) the extra fatty acids which are not being utilized by the cells. However, the liver does not have the enzyme necessary for complete catabolism of the fatty acids. This causes the discharge of the ketone molecules into the blood. The strange taste in the mouth and mild breath odor shows the presence of these ketones. Other body cells can utilize the ketones for energy. The brain can also utilize ketones contrary to the myth that the brain must be powered by glucose only; although, some areas of the brain still require glucose, which the body makes from amino acids or fats. The body begins to utilize the fatty acids for energy more efficiently after a few weeks and the ketone level drops to normal. This does not mean one is not losing weight. It means the body is becoming a more efficient fat burner.